Tips, Tricks, and Newb Questions!

Two other things that bother me:
What the heck is encumbering me so much? I have a military rucksack, and fitting SWAT armor for my torso (20+25=45, around 40% encumbrance I would think) but it says that I have 60% encumbrance, even though I’m not wearing anything else for my torso.
What does a dissector do? I’ve passed a couple of them in labs.